S195: MOMENTUM: PHASE 3 RANDOMIZED STUDY OF MOMELOTINIB (MMB) VERSUS DANAZOL (DAN) IN SYMPTOMATIC AND ANEMIC MYELOFIBROSIS (MF) PATIENTS PREVIOUSLY TREATED WITH A JAK INHIBITOR
Authors: S. Verstovsek, A. Vannucchi, A. Gerds, H. K. Al-Ali, D. Lavie, A. Kuykendall, S. Grosicki, A. Iurlo, Y. T. Goh, M. Lazaroiu, M. Egyed, M. L. Fox, D. McLornan, A. Perkins, S.-S. Yoon, V. Gupta, J.-J. Kiladjian, R. Donahue, J. Kawashima, R. Mesa
Journal: HemaSphere (2022)

Background: MMB, a novel oral ACVR1/ALK2 and JAK1/2 inhibitor, showed clinical activity on MF symptoms, red blood cell (RBC) transfusion requirements (anemia), and spleen volume in the SIMPLIFY trials. Aims: This pivotal phase 3 study of MF patients (pts) previously treated with a JAK inhibitor (JAKi) tested MMB vs DAN on key symptom, anemia, and spleen volume endpoints at 24 weeks (wks). Methods: Eligibility: Primary or post-ET/PV MF; DIPSS high risk, Int-2, or Int-1; MF Symptom Assessment Form Total Symptom Score (MFSAF TSS) ≥10; hemoglobin (Hgb) <10 g/dL; prior JAKi for ≥90 days, or ≥28 days if RBC transfusions ≥4 units in 8 wks or Gr 3/4 thrombocytopenia, anemia, or hematoma; palpable spleen ≥5 cm. Stratification: TSS (≥22 vs <22), palpable spleen (≥12 cm vs <12 cm), and RBC units transfused (0, 1-4, and 5+). JAKi taper and washout was ≥21 days. Randomization: 2:1 to MMB 200 mg QD plus DAN placebo or DAN 600 mg QD plus MMB placebo for 24 wks, after which pts could receive open-label MMB. Assessments: Pt reported symptoms using a daily eDiary and spleen volume by MRI or CT. The primary endpoint was TSS response (≥50% reduction from baseline [BL]) rate at wk 24. Secondary endpoints, assessed sequentially at wk 24, were RBC transfusion independence (TI) rate, splenic response rate (SRR; ≥25% reduction in volume from BL), change from BL in TSS, SRR (≥35% reduction from BL) and rate of zero transfusions since BL. Informed consent was obtained from all participants. Results: 94 of 130 (72%) MMB pts and 38 of 65 (58%) DAN pts completed the 24-wk randomized treatment (RT) phase. Median BL TSS were 28 (MMB) and 26 (DAN), Hgb were 8.1 (MMB) and 7.9 (DAN) g/dL, and platelets were 97 (MMB) and 94 (DAN) x109/L. BL TI was 13% (MMB) and 15% (DAN). BL mean spleen volume was 2367 (MMB) and 2288 (DAN) cm3. Prior JAKi was ruxolitinib in 195 pts (100%) and fedratinib in 9 pts (5%); mean duration of prior JAKi was 134 weeks. All primary and key secondary endpoints were met (Table). Most common Gr ≥3 treatment-emergent adverse events (TEAEs) in the RT phase of the study were thrombocytopenia (MMB, 22%; DAN, 12%) and anemia (MMB, 8%; DAN, 11%). Gr ≥3 infections occurred in 15% of MMB and 17% of DAN pts. Peripheral neuropathy (PN) occurred in 5 (4%) of MMB (all Gr ≤2) and 1 (2%) of DAN (Gr ≤2) pts in the RT phase, and none discontinued study drug due to PN. Overall, TEAEs led to study drug discontinuation in 18% of MMB and 23% of DAN pts, and serious TEAEs were reported in 35% of MMB and 40% of DAN pts, in RT phase. A trend toward improved OS up to wk 24 was seen with MMB vs DAN (HR=0.506, p=0.0719). Image:Summary/Conclusion: In symptomatic and anemic MF pts, MMB was superior to DAN for symptom responses, transfusion requirements, and spleen responses with comparable safety and favorable survival. MMB may address a critical unmet need, particularly in MF pts with anemia. NCT04173494.